Tertiary Sea Level Changes and Sequence Stratigraphic Framework in East China Sea Shelf Basin

The East China Sea shelf basin is a key area for setting up the sea level changes of Cenozoic in the West Pacific. Based upon the characteristics of seismic reflection, the analysis of sequence stratigraphy and depositional system, the high resolution chronostratigraphic framework has been set up by using the data of micropaleontologic biozone fossils. The relative sea level change curve has been set up by combining analysis of paleoecology, genetic facies, specific sedimentary structures and on lap recognized from the seismic profiles with study of geochemical characteristics. There are 4 2nd order basin cycles showing the long term sea level changes, and 22 3rd order cycles showing short term ones with relative changing ranges of 0-150 m. Transgression and regression showing long term sea level changes bear asymmetric feature, which indicates that the speed of transgression is faster than that of regression. There are a lot of differences when compared with Haq ’s curve. The sequence stratigraphic framework has also been set up and 3 tectonic sequences, 7 supersequences and 19 sequences have been subdivided for Tertiary in the East China Sea shelf basin. On the basis of detailed analysis of genetic facies and log facies, 9 sedimentary systems, 20 depositional assemblages and many genetic facies have also been recognized and investigated. Based on the studies mentioned above, the favorable source and reservoir facies of gas and petroleum are indicated.

Late Permian Sequence Stratigraphic Framework and Controlling Factors in Southern Yangtze Platform and Its Margin

Late Permian stratigraphic, sedimentary and paleotectonic studies along a corridor profile across the Yangtze paleocontinent and its southern margin reveal the sedimentary evolution, subdivide the depositional sequences, and reconstruct the stratigraphic framework based on lateral correlation and tracing of the bounding surfaces and depositional systems. This corridor profile transects the Yangtze craton and a molasse sag zone in its southern margin. It is demonstrated that the Late Permian sedimentary evolution along the investigated profile evidently resulted from the interplay of sea level change, differential subsidence and sediment supply within the given tectonic units. In the cratonic interior, high frequency sea level fluctuation exerts an important control on the formation of the third order and fourth order sequences, and is the basis for transfacies correlation. The evolution of sequence succession in the taphrogenic zone is so much affected by the intense tectonic subsidence that it is hardly correlatable to that in the cratonic interior.

Stratigraphic Framework of the Cryogenian in China

The Cryogenian is a critical period in the history of the Earth. It is marked by multiple extreme climate changes that caused alternating global glacial and interglacial intervals. These dramatically changed the sedimentary system, and metal ores and source rocks distributed widely during this period. Therefore, studying the Cryogenian stratigraphic framework and sedimentary basins is important to improve the stratigraphic resolution for metal mineral and hydrocarbon prospecting and exploration in China. This review paper firstly divides three tectonic-stratigraphic regions in China in the Cryogenian, including the tectonic-stratigraphic regions of Great South China, Xingmeng-Tarim, and North China. Secondly, geochronologic data and geological records are combined to clearly depict the Cryogenian sedimentary sequence of continental blocks and micro-continental blocks in different tectonic-stratigraphic regions. The results were used to propose a new comparison scheme of stratigraphy for the Cryogenian in China. Finally, according to differences of sedimentary evolution and tectonic evolvement, sedimentary basins and their lithofacies paleogeography are identified and summarized, respectively.

The Late Triassic Sequence-Stratigraphic Framework of the Upper Yangtze Region,South China

In the transitional period between the Middle and the Late Triassic, the Indochina orogeny caused two tectonic events in South China：（1） the formation and uplift of the Qinling-Dabie orogenic belt along the northern margin of the South China Plate, due to its collision with the North China Plate; and 2） the development of a 1300-km-wide intra-continental orogen in the southeastern part of the South China Plate, which led to a northwestward movement of the foreland thrust-fold zone. These tectonic events resulted in the ending of the Yangtze Platform, and were a stable paleogeographic factor from the Eidacaran to the end of the Middle Triassic. This platform was characterized by the widespread development of shallow-water carbonates. After the end of the Yangtze Platform, the upper Yangtze foreland basin（or Sichuan foreland basin） was formed during the Late Triassic and became a accumulation site of fluvial deposits that are composed of related strata of the Xujiahe Formation. In western Sichuan Province, the Xujiahe Formation overlies the Maantang Formation shallow-water carbonate rocks of the Xiaotangzi Formation siliciclastic rocks（from shelf shales to littoral facies）. The sequence-stratigraphic framework of the Upper Triassic in the upper Yangtze foreland basin indicates a particular alluvial architecture, characterized by sequences composed of（1） successions of low-energy fluvial deposits of high-accommodation phases, including coal seams, and（2） high-energy fluvial deposits of low-accommodation phases, including amalgamated river-channel sandstones. The spatial distribution of these fluvial deposits belonging to the Xujiahe Formation and its relative strata is characterized by gradual thinning-out, overlapping, and pinching-out toward both the east and south. This sedimentary record therefore expresses a particular sequence-stratigraphic succession of fluvial deposits within the filling succession of the foreland basin. The sequence-stratigraphic framework for the Upper Triassic in the Upper Yangtze region provides a record of the end of the Yangtze Platform and the formation of the upper Yangtze foreland basin.

Late Paleozoic Sequence-Stratigraphic Frameworks and Sea Level Changes in Dianqiangui Basin and Its Adjacent Areas with Systematic Revision of Regional Unconformities

The formation process of the Dianqiangui basin, a special basin, occurred after the Caledonian orogeny, in the south of Guizhou, the west of Guangxi and the southeast of Yunnan, experienced three periods: it began in the Devonian, persisted in the Carboniferous, and became fiercer in the Permian. Controlled by syndepositional fault-zones, varieties of isolated carbonate platforms, large and small, were developed in the background of a deep-water basin, namely, an inter-platform ditch. And a special paleogeographical Late Paleozoic pattern marked by “platform-basin-hill-trough” was produced in both the Dianqiangui basin and its adjacent areas. Affected by regional tectonic activities and the global changes in the sea level, the platform carbonates and coal measures superimposed each other cyclically on the attached platform. The reef-building on the isolated platform and the margin of the attached platform corresponds to the development of the shale succession in the deep-water basin. All of these elementary characteristics reflect a regular and sophisticated filling succession of the Dianqiangui basin, a result of the dual controls of the regionally tectonic activities and the eustacy. Based on the two elementary features of the third-order sequences, i.e. the regularity of sedimentary-facies succession in space and the simultaneity of environmental changes in time, 25 third-order sequences could be discerned in the Upper Paleozoic strata in the Dianqiangui basin and its adjacent areas. On the basis of the two kinds of facies-changing surfaces and the two kinds of diachronisms in stratigraphic records, the regional Late Paleozoic sequence-stratigraphic framework in the Dianqiangui basin and its adjacent areas can be established. There are two types of facies-changing surfaces and two types of diachronisms in stratigraphic records: the static type, a result of the change in sedimentary facies in space, and the dynamic type, a result of the change in time. These two types of facies-changing surfaces led to the generation of the two types of diachronisms: the diachronism of facies-changing surfaces that was formed by the static facies-changing surfaces, and the diachronism of punctuated surfaces that was formed by the dynamic facies-changing surfaces. The two types of facies-changing surfaces and the two types of diachronisms in stratigraphic records are the key to the establishment of the sequence-stratigraphic framework. The sequence boundaries could be divided geologically into four types: tectonic unconformity, sedimentary unconformity, drowned unconformity and their correlative surfaces. All of these four types can be further grouped into exposed punctuated surfaces and deepened punctuated surfaces. The tectonic unconformity is similar to Type Ⅰ sequence boundary, and the sedimentary unconformity is similar to Type Ⅱ sequence boundary defined by Vail et al.. In terms of sequence stratigraphy, the tectonic unconformities of the Ziyun movement, the Qiangui epeirogeny and the Dongwu revolution as well as the drowned unconformity in the transitional period from the Permian to the Triassic can be systematically defined and their geological characteristics are briefly presented.

Distribution regularity of the Ordovician reef-bank reservoir inside sequence stratigraphic ework in central Tarim Basin

Based on the integrated study of the outcrops, the seismic, drilling and logging data of Lianglitage formation in central Tarim Basin, the sequence stratigraphic framework of the platform margin is built, and the Lianglitage formation is divided into 3 third-order sequences. The vertical pattern and lateral distribution for carbonate reef-bank reservoir in sequence stratigraphic framework are analyzed. The reef-bank reservoir mainly developed in highstand system tract of sequence Ssq2, and distributed along the carbonate platform margin of the Middle-Late Ordovician in central Tarim Basin. The mudstone mound, organic reef, granule bank are vertically stacked. Laterally, the area of well shun3-shun4-shun2-shun6 are characterized by multiphase bank reservoir overlapping, and the area of well TZ82 -TZ44 - TZ161 -TZ24 - TZ26 are characterized by multiphase organic reef and bank overlapping. The reef-bank complexes in sequence Ssq2 are the main targets of exploration in central Tarim Basin.

Sedimentary architecture and distribution of intra-platform shoal in sequence framework of Permian Changxing Formation in central Sichuan Basin,SW China

Based on the comprehensive analysis of core, thin section, logging and seismic data, this study carried out the identification and comparison of Permian Changxing Formation sequences, clarified the typical sedimentary architectures of intra-platform shoal, investigated the vertical and horizontal development and distribution of intra-platform shoal in each sequence, and thus established the sedimentary evolution model of shoal body. The study results are reflected in four aspects.First, there are two complete third-order sequences(SQ1 and SQ2) in Changxing Formation in central Sichuan Basin. SQ1 is generally thick in the north and thin in the south, and SQ2 shows a thickness differentiation trend of “two thicknesses and three thinnesses”. Second, the Changxing Formation in central Sichuan Basin mainly develops intra-platform shoal, inter-shoal sea and intra-platform depression subfacies. In the vertical direction, the intra-platform shoal mainly presents two typical sedimentary sequences: stable superposed and high-frequency interbedded. Third, the stable superimposed sedimentary sequence is developed in the shoal belt at the edge of intra-platform depression, which is composed of two shoal-forming periods and located in the highstand systems tracts(HSTs) of SQ1 and SQ2. The high-frequency interbedded sedimentary sequence is developed in the southern shoal belt of intra-platform depression, which is composed of four shoal-forming periods and mainly located in the HST of SQ2. Fourth, during the SQ1 deposition, the intra-platform shoal was mainly developed at the edge of the intra-platform depression on the north side of the study area, and the inter-shoal sea subfacies was mainly developed on the south side. During the SQ2 deposition, the intra-platform shoal was widely developed in the area, forming two nearly parallel intra-platform shoal belts. The study results provide direction and ideas for exploration of Changxing Formation intra-platform shoal reservoirs in central Sichuan Basin.

珠三坳陷珠江组一段沉积体系演化过程及其控制因素

珠江组一段沉积时期是珠三坳陷沉积体系演变的重要时期,由早期的大范围三角洲沉积体系演化为晚期的浅海陆架沉积体系,对其演化过程及控制因素展开研究,不仅有利于揭示海侵过程中沉积体系演化过程,而且对浅海陆架有利沉积相带预测具有指导意义。综合利用岩心、测井以及高分辨率三维地震资料,建立了珠三坳陷珠江组一段四级层序地层格架,通过地质-地球物理结合方法查明了珠江组一段沉积体系的时空演化特征,并讨论了沉积演化的主控因素。研究表明:珠三坳陷珠江组一段可划分为PS1、PS2、PS3、PS4共4个四级层序。PS3和PS4时期主要发育三角洲前缘沉积,具有水下分流河道、分流间湾、河口坝和远砂坝等沉积微相组合;PS1和PS2时期以浅海陆架沉积体系大规模发育为特征,在研究区西部发育潮流砂脊,东部发育滨外砂坝。珠三坳陷沉积体系的平面展布以及垂向演化受相对海平面变化、物源供给强度、构造沉降与古地貌等综合控制。水下分流河道、潮流砂脊与滨外砂坝等微相砂岩占比高且物性好,为油气储集的有利沉积相带。

海上稀疏井区高精度地层格架约束下的地震沉积学刻画——以东海盆地西湖凹陷中央背斜带X区块古近系花港组为例

海上工区面积辽阔,单井资料匮乏,花港组内部横向上的沉积微相界定存在争议、纵向上的沉积演化规律不明。为充分挖掘现有井、震资料的地质解释潜力,选取东海盆地西湖凹陷中央背斜带X区块古近系花港组为研究对象,提出了井-震小波变换建立高精度等时地层格架、井点沉积相标志定相类型、分频RGB属性刻画沉积相展布以及古地貌恢复辅助沉积相演化规律分析的地震沉积学解释技术。研究结果表明:(1)测井-地震小波变换结果有较好的一致性,可将研究区花港组分为花港组上段(花上段)3个(H1—H3)和花下段5个(H4—H8)四级旋回,并在此基础上建立高精度等时地层格架。(2)根据岩心相、测井相和地震相相互印证,确认研究区花港组沉积期为辫状河三角洲沉积环境。分频振幅属性验证不同厚度砂岩层在15,30和45 Hz单频体的振幅响应明显,采用分频RGB属性融合可在平面凸显不同沉积体的边界。(3)研究区H1和H2旋回整体为三角洲前缘沉积,H3—H6旋回为浅水背景下的三角洲平原-前缘沉积,H7和H8旋回为辫状河三角洲平原沉积,砂层组沉积相垂向演化受控于物源供给、相对湖平面高低和古地貌形态。在井-震时频分析建立等时地层格架基础上,通过相关性分析优选属性进行RGB融合能够凸显不同厚度砂岩的展布,减少了人为主观因素的影响,提升了沉积体边界的识别能力,可为其他井网稀疏地带沉积相刻画提供借鉴。

鄂尔多斯盆地庆城油田延长组页岩层系层序地层与沉积相特征

鄂尔多斯盆地三叠系延长组页岩层系蕴藏着丰富的油气资源,但其层序格架及沉积相展布存在较大的争议,从而影响着页岩油气的精细勘探与开发。以庆城油田西233区块为例,应用岩心、测井及最新的三维地震资料重构了层序地层格架及沉积相分布。研究表明,在延长组原长81—长32砂组内,地层向湖盆中心呈进积叠置样式,可分为2个长期基准面旋回和10个中期基准面旋回。在每个中期旋回内,向盆地方向的古地貌依次为浅水带、斜坡带和盆底带。浅水带主要发育三角洲;斜坡带发育重力流水道,顺斜坡呈窄条带状分布;在盆底带近端发育重力流朵叶体沉积,砂体夹于泥页岩中,而盆底带远端主要为深湖页岩夹滑塌体沉积。原长7油层组页岩层系为1套穿时地层,由多个中期旋回的斜坡带下部、盆底带湖底扇砂体和半深湖—深湖泥岩组成。这一研究不仅对鄂尔多斯盆地夹层型页岩油的有效开发(开发区优选及水平井部署)具有重要的指导作用,亦对拗陷湖盆层序与沉积演化理论的发展具有一定的促进作用。

High-Resolution Sequence Stratigraphy and Coal Accumulating Models of the Permo-Carboniferous Coal Measures in Southwestern Shanxi

The Qinshui Basin in southeastern Shanxi Province is an important base for coalbed methane exploration and production in China.The methane reservoirs in this area are the Carboniferous and Permian coals and their thickness are strongly controlled by the depositional environments and the sequence stratigraphic framework.This paper analyzes the high-resolution sequence stratigraphy of the Permo-Carbo-

Study on Carbonate Sequence Stratigraphy of Ordovician in Northern Ordos Basin

The formation of carbonates is different from that of siliciclastics. The controlling factors, such as the in-situ production of carbonates the transport, local variation in depositional processes and the way of dispersal are unique to carbonates systems, and have resulted in the formation of a wide variety of stratal patterns. The authors believe that all the factors influencing the formation of carbonates, such as the evolution of carbonate platform, transgression and regression, drowning and exposing of the platform, should be taken into consideration during the study of carbonate sequence stratigraphy.This paper attempts to summarize the study procedure in outcrop sequence stratigraphy and to describe the integrated identification of condensed section, first flooding surface and maximum flooding surface, so that the framework of high-resolution sequence stratigraphy can be constructed. During the Sandokan in early Ordovician, a carbonate-siliciclastic ramp was developed in northern Ordos, which changed into a carbonate rimmed shelf or a distally steepened ramp during the Zhuozishan and Kelimoli. It was the break in the Wulalike and Middle Ordovician,changing the sedimentary setting into an aulacogen According to the basin evolution, the authors have established some different idealized models for depositional sequences and systems tracts.

四川盆地凉高山组层序地层格架及有利勘探区优选

针对四川盆地凉高山组层序地层格架的建立及有利区优选复杂多变的难题,利用四川盆地凉高山组测井及地震等资料,识别不同尺度的标志层,建立标志层的测井-地震识别标准,利用区域格架线搭建层序地层格架,通过井震结合分析,厘清全盆地凉高山组岩性、相带变化关系,并结合有利相带分布及“源储”配置关系,优选有利勘探区。研究表明:以水进界面作为标志层,搭建层序地层格架,能够快速确定烃源岩与储层发育层位、厚度及分布范围;优选凉高山组凉一3亚段为有利烃源岩发育层位,凉二1亚段为有利储层发育层位;凉一3亚段烃源岩发育区,即盆地东北部及边缘龙岗-梁平一带页岩厚度较大,最厚处可达60~80 m,是下一步勘探的有利目标区。研究成果丰富了四川盆地凉高山组层序地层、沉积演化及勘探区优选等相关勘探研究工作,也为同类油藏的勘探开发提供了理论依据。

松辽盆地梨树断陷构造沉积学特征及发育机制

梨树断陷是一个具有复杂构造沉积特征的箕状断陷湖盆,在松辽盆地深层断陷群中具有代表性。本文以大量的三维地震与钻井资料为基础,通过构造解释与沉积学分析,揭示该区整个断陷过程中的构造与沉积特征,总结其演化规律,分析其控制因素,明确盆地的构造沉积学特征及演化机制;一方面为该区深层储层与圈闭预测研究提供地质依据,另一方面也为松辽盆地其他断陷的构造沉积学深入研究提供实例参考。研究表明,早白垩世的左旋拉伸应力背景及数次挤压构造活动造就了该区断陷过程中发育了多个亚构造阶段,经历了由断陷初期的多个“小而陡”的次级小断陷,向强烈断陷期的一个“西断东超”统一箕状断陷湖盆,再向断陷晚期的“盆缓、域广”浅水湖盆的演化历程。在断陷期的不同阶段,不整合面类型多样、成因各异;初始裂陷阶段区域地层抬升与断块掀斜均有发生,造成不整合的多类型样式;强烈断陷期更多发育断块旋转、掀斜造成的角度不整合;而在断陷晚期,平行不整合占据了更大的不整合面积比例,体现了地层整体抬升与沉降的结果。盆地沉积充填经历了由湖-扇沉积体系向辫状河体系的演变过程;强烈断陷阶段的各层序呈现“低位域逐渐萎缩,高位域所占比例不断增大”的层序结构变化特征;裂陷晚期层序则以“横向连续、纵向加积”为主要层序结构特征。

川西北部地区寒武系—奥陶系的地层格架新认识及地质意义

为查明川西北部地区是否发育完整的寒武系—奥陶系的地层格架,以赋予该地区地震资料新提出的德阳—绵阳拗陷地质意义以及支撑厘清该地区构造—沉积演化过程,从而更加精准服务于油气的风险勘探部署工作。利用野外剖面精测以及锆石U-Pb同位素定年分析等手段对川西北部地区多个寒武系—奥陶系剖面的岩石类型、沉积序列以及年代归属等进行了研究。研究结果表明:①川西北部地区原定义的“筇竹寺组”顶部最大沉积年龄峰值约为505 Ma,磨刀垭组最大沉积年龄约为479 Ma;前者限定了筇竹寺组顶部的沉积时限晚于芙蓉世,后者限定了其沉积时限晚于中奥陶世。综合表明研究区可能发育连续的寒武系—奥陶系,并非缺失中上寒武统—中下奥陶统。②川西北地区寒武纪—奥陶纪时期发育潮坪→浅水陆棚→滨岸→三角洲→碳酸盐岩台地沉积环境,经历了细粒碎屑岩→粗碎屑岩→碳酸盐岩的沉积充填过程。③沉积环境可能受到加里东期的郁南、都匀、广西等多幕次构造运动的影响。④研究结果不仅为前人新提出的该地区发育寒武纪—奥陶纪局部拗陷提供地质证据,而且为四川盆地西北缘构造—沉积格局的进一步厘定奠定了基础。

扬子克拉通西北缘成冰系冰川沉积特征和地层格架

扬子克拉通西北缘成冰系沉积学研究相对较少,大巴山城口地区更为薄弱,特别是成冰系木座组/明月组和代安河组是否存在冰川沉积缺乏详细的沉积学解释,制约了对扬子克拉通成冰纪沉积演化过程的理解,也不利于该时期地层格架的厘定和区域对比。本文选择城口地区四个典型成冰系剖面开展精细地层学和沉积学解剖,识别出了发育冰川擦痕砾石、坠石和冰下软沉积变形等冰川沉积标志,证明代安河组和木座组/明月组为冰川成因,并划分出陆相冰川、冰缘和海相冰川等沉积相类型。进而依据岩石组合、沉积特征、上下地层结构、地化指标(如化学蚀变指数等)和碎屑锆石U-Pb年龄等特征将代安河组二分,一段对比古城组,二段对比大塘坡组,木座组/明月组对比南沱组。在此基础上开展了区域对比,重新厘定扬子克拉通西北缘成冰系的地层格架,认为其可与相邻神农架以及扬子克拉通东南缘对比。恢复了城口—神农架地区成冰系沉积演化过程:斯图特冰期发育着由冰海至陆地再至冰海的冰川进退旋回,随后间冰期的广泛海侵形成了碳质粉砂质泥岩为代表的潟湖环境;随着全球气温再次下降引发马雷诺冰期,经历了多次从冰海近缘至冰海远缘的冰川沉积动态演化过程,并伴随有冰盖打开最终至成冰纪结束。研究成果厘定了扬子克拉通西北缘成冰系的对比划分,为扬子克拉通成冰系对比提供新的基础资料和重要依据。

稠油区块多元驱油开发模式研究与试验

C13块为普通稠油块状油藏,历经多年注水开发,受出砂、井况等问题影响,开发效果较差,整体处于“双低”开发状态。开展精细地质体刻画,重新落实区块构造及剩余油分布情况,为后续的开发调整提供了物质基础。根据南北区域不同的地质条件,分区分方式制定调整策略,北部油品性质较差,重构井网后按照蒸汽吞吐配合注水补能的开发方式进行调整;南部区域立足注水开发,利用深部调驱改善纵向动用状况。试验井组增油效果显著,下步可扩大实施规模。调整后,预计区块最终采收率可达到19.1%,较标定采收率提高6.1%,开发效果得到有效改善,为同类型油藏提供有力借鉴。

川中二叠系长兴组层序格架内台内滩沉积构型与分布规律

基于岩心、薄片、测录井及地震资料的综合分析,开展川中二叠系长兴组层序识别与对比,明确台内滩的典型沉积构型,系统研究各层序台内滩的纵横向发育规律,进而建立滩体的沉积演化模式。研究表明:(1)川中地区长兴组发育两个完整三级层序,SQ1层序整体为北厚南薄,SQ2层序呈“两厚三薄”的厚度分布特征。(2)川中地区长兴组发育台内滩、滩间海和台内洼地亚相,台内滩在垂向上主要发育稳定叠加型和高频互层型两种典型沉积序列。(3)台洼边缘滩带发育稳定叠加型沉积序列,由两个成滩期构成,分别位于SQ1和SQ2层序的高位域;台洼南侧滩带发育高频互层型沉积序列,由4个成滩期构成,主要位于SQ2层序的高位域。(4)SQ1层序沉积时期,台内滩主要发育在研究区北侧的台洼边缘,南侧整体为滩间海亚相;SQ2层序沉积时期,台内滩在区内广泛沉积,形成两个近于平行的台内滩带。研究结果为川中地区长兴组台内滩勘探提供了方向和思路。

准噶尔盆地东北缘石炭系年代—地层格架:对卡拉麦里洋闭合时限的启示

卡拉麦里地区洋—陆转换是中亚增生造山演化的重要地质过程,其对准噶尔石炭纪盆地发育与演化以及油气地质条件具有重要的控制作用;厘定卡拉麦里洋的闭合时限是揭示洋—陆转换的关键。但卡拉麦里地区的石炭纪地层划分尚未统一,严重制约了对该洋盆演化过程的认识。本文在回顾总结卡拉麦里地区的石炭纪地层划分沿革的基础上,基于岩石地层、古生物地层以及同位素年代学资料,对卡拉麦里断裂南侧的石炭纪地层进行了重新梳理,建立了卡拉麦里地区石炭系年代—地层格架。研究结果显示卡拉麦里地区石炭纪地层层序在结构上具有东西分段差异。卡拉麦里东段(双井子地区)和西段(白碱沟地区)下石炭统底部均为滴水泉组碎屑沉积,时代为359~350 Ma;其上覆地层均为松喀尔苏组a段,是一套火山—沉积序列,其顶、底火山岩年龄将其形成时代限定为350~332 Ma;松喀尔苏组b段碎屑沉积仅发育在卡拉麦里西段,其时代为332~323 Ma;西段上石炭统为巴塔玛依内山组,是一套火山—沉积序列,其测得最老和最年轻的火山岩年龄将其时代限定为323~306.5 Ma;而东段上石炭统为石钱滩组碎屑沉积,在盆内偶见火山碎屑岩及火山岩,时代为308~299 Ma。同时结合前人在卡拉麦里缝合带北侧地层古生物学及沉积学,断裂两侧火山岩以及南侧的地震地层学研究结果,认为卡拉麦里洋闭合于早石炭世晚期(332~323 Ma)。

基于频谱属性趋势分析和小波变换的层序界面识别方法——以珠三坳陷中新统珠江组—韩江组为例

珠江口盆地珠三坳陷勘探程度相对较低,建立层序地层格架是有效开展油气勘探的重要基础。文中运用基于测井曲线的频谱属性趋势分析(INPEFA)和小波变换技术,识别各级层序界面和最大海泛面。即通过对自然伽马曲线进行最大熵谱分析,得到INPEFA曲线;利用INPEFA曲线的趋势和拐点,提取自然伽马曲线隐藏的周期性特征,进而划分出不同级次的层序界面;同时利用小波变换技术,对自然伽马曲线重构,分析重构后的小波系数曲线和时频色谱图,并采用曲线的异常震动和时频色谱图的能量变化识别三级层序界面和最大海泛面。研究结果表明,在珠江口盆地珠三坳陷中新统珠江组—韩江组识别出3个二级层序界面及6个三级层序界面,划分了2个二级层序和8个三级层序。利用文中方法,各级层序界面识别更直观、更明显,同时能够提高旋回划分及对比的精度和准确性,为研究区后续勘探开发提供技术支撑。